Psychedelics for OCD Explained: Sorcha O’Connor PhD(c) | Psychedelic Medicine Podcast

Summary

The episode discusses obsessive-compulsive disorder (OCD), its cognitive features and current treatments, and the rationale for studying psilocybin. The PsilOCD study’s results had not yet been released at the time of the interview, so the episode does not establish whether psilocybin was effective in that trial.

OCD and cognition

OCD involves obsessions—unwanted thoughts—and compulsions, which may be physical or mental actions intended to ease distress or prevent feared outcomes. Rituals can bring temporary relief, reinforcing belief in the feared threat and the perceived need to repeat the ritual.

OCD can focus on many topics, not only contamination or order. Examples discussed include health, identity, responsibility for others, and fears about data or safety. OCD is associated with anxiety and can co-occur with conditions such as panic disorder, phobias, generalized anxiety disorder, and PTSD. The interview also describes the cortico-striato-thalamo-cortical loop as a brain circuit associated with OCD symptoms.

Research discussed in the episode points to possible differences in cognitive flexibility and metacognitive confidence. In an attentional set-shifting task, people with OCD may learn rules but have more difficulty switching between perceptual dimensions. This difficulty has also been observed in some unaffected relatives, leading researchers to consider whether it could be a trait marker. People with OCD may also report less confidence on some tasks, even beyond their specific fears.

OCD is classified in the DSM-5 among obsessive-compulsive and related disorders. The episode distinguishes OCD from obsessive-compulsive personality disorder (OCPD), which is described as involving personality traits such as perfectionism and rigidity.

Treatments and research

Exposure and response prevention (ERP) is presented as a leading psychological treatment. It involves gradually confronting feared situations or thoughts while refraining from related compulsions. The aim is to test feared predictions and learn that the feared outcome does not necessarily follow.

SSRIs are commonly used and may help some people, often at higher doses for OCD than for depression. The guest characterizes their benefits as moderate and notes that side effects or lack of response can be barriers. Other medicines, including antipsychotics or mood stabilizers, may sometimes be used as adjuncts.

A 2006 University of Arizona pilot study gave nine participants low, moderate, and high doses of psilocybin. The guest reports that symptom reductions of at least 25% were seen on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), with reported reductions ranging from 25% to 100%. Follow-up covered only the first 24 hours, a major limitation.

PsilOCD, led by Sorcha O’Connor, was described as a feasibility study of a lower psilocybin dose, chosen partly to make the experience more tolerable for people who may be sensitive to bodily sensations or health-related fears. The study had finished dosing its final participant in July 2024, but its results were not public at the time of the episode.

The study design, as described, included:

• Participants received 1 mg as an active placebo on the first dosing day and 10 mg on the later dosing day, four weeks afterward.
• The overall study lasted about ten weeks, with a four-week follow-up after each dose.
• Researchers collected symptom ratings, cognitive-test data, and EEG measures. Symptoms were assessed at seven points during the study.
• Each participant had two therapists or guides for preparation and integration. Dosing sessions used supportive, non-directive care rather than a specific OCD therapy such as ERP.

The guest suggests that future research could test combining psilocybin with OCD-focused therapy, potentially using a period of increased neuroplasticity after dosing to support learning. This is presented as a research possibility, not an established treatment.

LSD was mentioned in case reports and anecdotes, while ketamine was described as having mixed evidence for OCD. The guest also speculated that short-acting psychedelics such as DMT could be too intense for some people with OCD. These comments were not presented as definitive findings.

Researchers and sources featured

• Sorcha O’Connor — neuroscience researcher and leader of the PsilOCD study.
• Dr. Lin Marie Morski — podcast host and interviewer.
• Sarah — therapist involved in the PsilOCD study; no surname was given.
• Dr. Michael Greenberg — psychologist whose writing and talks on rumination were recommended.
• University of Arizona researchers — investigators in the 2006 psilocybin pilot; individual names were not provided.
• Yale and Johns Hopkins research teams — mentioned as conducting studies using a higher psilocybin dose; individual researchers were not named.

Sources and measures discussed included the DSM-5, the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the attentional set-switching task (including intradimensional–extradimensional set shifting), and the PsilOCD feasibility study.